core-js/modules/esnext.array.last-index.js

'use strict';
// TODO: Remove from `core-js@4`
var DESCRIPTORS = require('../internals/descriptors');
var addToUnscopables = require('../internals/add-to-unscopables');
var toObject = require('../internals/to-object');
var lengthOfArrayLike = require('../internals/length-of-array-like');
var defineBuiltInAccessor = require('../internals/define-built-in-accessor');

// `Array.prototype.lastIndex` getter
// https://github.com/keithamus/proposal-array-last
if (DESCRIPTORS) {
  defineBuiltInAccessor(Array.prototype, 'lastIndex', {
    configurable: true,
    get: function lastIndex() {
      var O = toObject(this);
      var len = lengthOfArrayLike(O);
      return len === 0 ? 0 : len - 1;
    }
  });

  addToUnscopables('lastIndex');
}